Drill bit assembly having detachable blades



p 1967 R. J. BLANTON 3,339,648

' DRILL BIT ASSEMBLY HAVING DETACHABLE BLADES 5 Sheets-Sheet 1 Filed June 25, 1965 iii!!! a INVENTOR Roscoe J. Blonfon ATTORNEYS DRILL BIT ASSEMBLY HAVING DETACHABLE BLADES Filed Juhe' 25, 1965 5 Sheets-Sheet 2 INVENTOR 39 Roscoe J. Blomon M 40 BY ATTORNEYS Sept. 5, 1967 R. J. BLANTON 3,

DRILL BIT ASSEMBLY HAVING DETACHABLE BLADES Filed June 25, 1965 5 Sheets-Sheet 5 INVENTOR Roscoe J. Blomon ATTORNEYS United States Patent 3,339,648 DRILL BIT ASSEMBLY HAVING DETACHABLE BLADES Roscoe J. Blanton, Dallas, Tex., assignor to Gold Digger Bit Co., Greenville, Tex., a corporation of Texas Filed June 25, 1965, Ser. No. 466,972 11 Claims. (Cl. 175412) ABSTRACT OF THE DISCLOSURE A drill bit assembly having a body formed of upper and lower detachably-connected, tubular sections which coact to support a plurality of cutter elements in depending relation to the lower section. The latter has upright grooves for receiving the complementary shanks of the cutter elements and an annular chamber, formed by the coaction of the body sections, at the upper end of the grooves for confining the arcuate heads of the cutter elements. Coacting shoulders on the body sections externally of the annular chamber for abutting engagement when the top and bottom walls of said chamber are in clamping engagement with the complementary upper and lower surfaces of the heads of the cutter elements, the shoulder of the upper body section simultaneously engaging upwardly-facing surfaces of the shanks of said elements to prevent axial, radial and rotational displacement of said elements. Preferably, the shoulders of the body sections are perpendicular to the longitudinal axis of the drill bit body so that loads imposed on the cutter elements are transmitted axially of said body.

This invention relates to new and useful improvements in drill bit assemblies having detachable cutter elements.

The novel drill bit assembly disclosed herein includes a body having an upper section or sub adapted to be connected to the lower end of a drill pipe and coacting with a lower section or head to support a plurality of cutter elements or blades which depend below the head. Upright channels or grooves are formed in the head of the bit body for receiving and confining the complementary shanks of the cutter elements, and an annular chamber or groove is provided above the channels by the coaction of said head with the sub for confining the arcuate, enlarged upper ends or mounting plates of said elements. The head and sub have coacting shoulders externally of the annular chamber for abutting each other when the top and bottom surfaces or walls of said chamber are in clamping engagement with the complementary upper and lower surfaces of the mounting plates. Also, the shoulder of the sub is adapted to simultaneously engage upwardly-facing shoulders or surfaces of the shanks of the cutter elements whereby axial, radial and rotational displacement of said elements is prevented. It is noted that the shoulders as well as the top and bottom walls of the chamber are perpendicular to the longitudinal axis of the drill bit body so that loads imposed on the cutter elements are transmitted axially of said body to the drill pipe. In addition, the cutter elements are readily removable for replacement or repair and no special tools are required to detach said elements from the drill bit body.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, wherein an example of the invention is shown, and wherein:

FIG. 1 is a side elevational view, partly in section, of a drill bit assembly constructed in accordance with the invention,

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FIG. 2 is a bottom plan view of the assembly with one of the cutter elements or blades being removed,

FIG. 3 is an enlarged, perspective view of one of the cutter elements,

FIG. 4 is a longitudinal, sectional view taken on the line 4-4 of FIG. 1,

FIG. 5 is a cross-sectional view, taken on the line 55 of FIG. 4, with one of the cutter elements being removed,

FIG. 6 is a cross-sectional view taken on the line 6-6 of FIG. 4, and

FIG. 7 is an exploded, perspective view showing the head and the lower portion of the sub of the drill bit body and two of the cutter elements.

In the drawings, the numeral 10 designates the body of a drill bit assembly having an elongated, tubular upper section or sub 11 and a coacting, substantially cylindrical lower section or head 12 for supporting a plurality of detachable cutter elements or blades 13. A screwthreaded box or socket 14 is provided at the upper end of the sub 11 for connection with the lower end of the usual drill pipe (not shown) and upright knockout lugs 15 may be suitably secured to the exterior of the medial portion of said sub, which portion is of reduced diameter and wall thickness, to facilitate assembly and disassembly of the drill bit body. Except for its reduced medial portion, the sub may be of the same diameter as the head 12. The lower portion of the bore of the tubular sub has internal coarse screwthreads 16 for engagement by the complementary external screwthreads 17 of an elongated, tubular member or pin 18 of reduced diameter and upstanding from the head 12 so as to form a coaxial continuation or extension thereof (FIGS. 4 and 7). An axial bore 19 extends throughout the head and its pin 18 and communicates with the bore of the sub 11 for conducting drilling fluids to the lower end of said head in the usual manner.

The sub has an annular, downwardly-facing radial shoulder or surface 20 at its lower extremity for abutting engagement with an upwardly-facing complementary shoulder or surface 21 at the upper end of the head 12 when the pin is screwthreaded into said sub. As shown by the numeral 22, the screwthreads 17 terminate above the lower end portion of the pin 18 to provide a continuous cylindrical surface on said pin adjacent the sub and head shoulders 20 and 21. An annular, internal recess 23 is formed in the shoulder of the sub 11 by enlarging the lower end of its bore in concentric, spaced relation to the cylindrical surface 22 of the pin for coacting with a substantially complementary recess 24 in the shoulder of the head to provide an annular chamber or groove 25, said pin surface forming the inner wall of the groove. The sub recess 23 is of much greater depth than the head recess 24, whereby the major portion of the chamber 25 is disposed within the lower end of the sub.

Equally-spaced, tangentially-directed channels or grooves 26 extend axially throughout the exterior of the head 12 so as to interrupt the recess 24 (FIG. 5) and are rectangular in cross-section except for the curvature of said head exterior (FIGS. 2 and 7). As shown by the numeral 27 in FIGS. 4 and 5, the fiat bottom wall of each groove 26 has its clockwise or leading margin alined with the cylindrical surface 22 of the lower end portion of the pin. Due to the tangential disposition of the grooves, the leading walls thereof are of greater width than the trailing walls of said grooves (FIGS. 2 and 5). When four grooves are provided, the clockwise (counterclockwise in FIG. 2) or leading walls of opposed grooves are parallel and in substantial alinement; however, it is noted that three or any other suitable number of grooves may be employed depending upon the use and diameter of the drill bit assembly.

The chamber 25 and grooves 26 coact to support the detachable cutter elements or blades 13 for replacement and repair. Although subject to variation, each blade includes an elongated shank 28 which is substantially rectangular in cross-section and substantially complementary to each of the grooves but which is of a width much greater than its thickness and the depth of the groove so as to project laterally from the head 12. Each blade shank has a flat inner face 29 for engaging the bottom wall of each groove 26, a fiat leading face 30 for engaging the leading wall of the groove, a trailing face 31 parallel to and of less width than the leading face for engaging the trailing wall of said groove, and a substantially arcuate or bevelled outer face 32 in concentricallyspaced relation to the exterior of the head. A cutting edge 33 is provided at the juncture of the leading and outer faces 30 and 32 due to the curvature or bevel of said outer face receding counterclockwise (FIGS. and 6). As shown in FIGS. 1 and 4, the shank 28 is of sufficient length to depend from each groove below the head 12 and may have an enlarged lower end portion or tip 34 in spaced relation to said head.

Preferably, the enlarged tip 34 of each shank is offset inwardly of the inner face of the shank so that the inner portion of the tip underlies the bore 19 of the head, and the leading face 30 and cutting edge 33 are coextensive with said shank and its enlarged tip. A downwardlydirected, V-shaped tooth 35 may be formed on the lower end of each tip by downwardly-converging, flat bottom surfaces 36 and have its apex or point 37 closer to the outer margin than to the inner margin of the tip (FIGS. 1, 3, 4 and 7); however, the apex of the tooth is disposed within the circumference of the drill bit body so as to underlie the head 12 and sub 11 as well as the coacting shoulders 21 and 20 thereof. The bottom surfaces 36 are inclined upwardly toward the trailing face 31 of the shank, which face is substantially coextensive with the tip, to provide a complementary cutting edge 38 at the lower margin of the tooth 35. A reinforcing rib 39 may extend longitudinally of the trailing face adjacent its outer margin from the outer bottom surface of the tip 34 to the intermediate portion of the shank 28, and the lower margins of said face and rib may be relieved adjacent the bottom surfaces as shown at 40. The inner portion of each tip may be substantially triangular in horizontal cross-section and have an upright, flat surface 41 converging inwardly from the trailing face 31 toward the leading face 30 which may be relieved to provide an inwardly-directed tooth 42. Below the tooth 42, an upright cutting edge 43 is formed on the inner margin of the V-shaped tooth 35 in parallel relation to the cutting edge 33 by a flattened surface 44.

For directing drilling fluid against the leading faces 30 of the enlarged tips 34 and particularly the teeth 35, grooves or recesses 45 extend tangentially of the lower extremity of the bore 19 of the head 12 and have their lower'ends terminating ahead of said leading faces (FIGS. 2, 4 and 7). V-shaped grooves or recesses 46, of downwardly-increasing depth and width, extend longitudinally of the exterior of the head between its grooves 26 to facilitate flow therearound as well as reduce the weight of said head. Also, the lower extremity of the head 12 may be relieved, as shown at 47 and 48, for the same purposes. Although not shown, it is readily apparent that the cutting edges of the blades 13 may have the usual hard metal inserts. Since this invention relates primarily to the mounting of the blades, the particular configuration of the enlarged lower ends or tips 34 is not critical and is subject to variation.

An enlarged mounting head or plate 49 upstands from the inner portion of the shank 28 ofeach blade 13 and is of transverse arcuate contour for seating engagement in the annular chamber 25 formed by the coaction of the recesses 23 and 24 with the cylindrical surface 22 of the pin 18 (FIG. 4). The plate 49 is relatively thin, having arcuate upright inner and outer surfaces 50 and 51 complementary to the inner and outer walls of the chamber,

fiat upper and lower faces 52 and 53 for seating engagement with the top and bottom walls of said chamber (FIGS. 3, 4 and 7) and upright, flat end surfaces 54. As shown in FIGS. 1, 5 and 6, the end surfaces 54 of adjacent mounting plates are adapted to be disposed in close proximity and need not engage one another. Since the grooves 26 for the shanks of the blades extend tangentially of the recess 24, said shanks extend tangentially of the plates 49 which have intermediate portions of their inner surfaces 50 in alinement with the inner faces 29 of said shanks adjacent the leading faces 30 of the latter (FIG. 3). Triangular fillets or webs 55 and 56 extend between the lower margin of each plate and the upper margin of the leading and trailing faces of each shank for reinforcing the plate (FIGS. 5 and 7) and the recess 24 is enlarged or relieved at 57 and 58 to receive the webs which have their lower surfaces flush with the lower face 53 of said plate.

Each shank 28 has a fiat upper face or shoulder 59 immediately outward of the mounting plate 49 and flush with the upper surfaces of the webs 55 and 56 for engagement, with said upper surfaces, by the shoulder 20 of the sub 11 when said shoulder engages the shoulder 21 of the body 12 (FIGS. 1 and 4). A downwardly and outwardly bevelled surface 60 may extend from the shoulder 59 to the outer face 32 of each shank. The height of each mounting plate is such that its upper and lower faces 52 and 53 engage the top and bottom walls of the chamber 25 simultaneously with the engagement of the shoulder 20 with the shoulders 21 and 59 to provide a four point contact, i.e., the mounting plate engages the sub and head and said sub engages the head and shank. Since the upper and lower surfaces of the webs are flush with the shoulder 59 of each shank and the lower face 53 of each plate, respectively, the surficial contact of each blade with the sub 11 and head 12 is amplified to increase the rigidity of the detachable mounting of the blade. The plate 49 is positively clamped against axial movement by the engagement of its upper and lower faces with the top and bottom walls of the chamber. Lateral or radial displacement of the plate is prevented by the close confinement of the inner and outer surfaces 50 and 51 of said plate by the inner and outer walls of the chamber 25, the annular spaces shown in FIGS. 1 and 4-6 being sufficient only to permit insertion and removal of said plate. Due to the shank 28 of each blade 13 being complementary to each groove 26 of the head as well as the webs 55 and 56 being complementary to the recess portions 57 and 58 of said head, rotational displacement of the blade is prevented. The engagement of the sub shoulder 20 with the shank shoulder 59 assists in preventing relative axial movement of the blade and, with the engagement between the shoulders 20 and 21, transmit the load imposed on said blade to the drill pipe through the sub.

It is noted that the shoulders 20', 21 and 59, the plate faces 52 and 53 and the top and bottom walls of the chamber 25, all of which function as shoulders, are horizontal or perpendicular to the longitudinal or vertical axis of the drill bit body whereby all loads are transmitted longitudinally or vertically of said body. This is important because it minimizes the tendency of the blades 13 to cant or wobble during drilling operations. Since the enlarged lower ends or tips 34 of the blades are spaced below the lower end of the head 12, said blades may be readily removed for replacement or repair. The screwthreaded pin 18 of the head is of sufficient length to permit partial unscrewing of said head from the sub 11 and spacing of the shoulders 20 and 21 apart whereby the plates 49 of the blades may pass therebetween upon lifting of said blades to move said plates out of the recess 24. The new or repaired blades may be inserted by reversing this simple procedure.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A drill bit assembly including a body having upper and lower tubular sections, a tubular pin upstanding axially from the lower section and screwthreaded in the bore of the upper section for connecting the body sections to each other, the lower end of the bore of said upper body section being enlarged to provide an annular downwardly opening recess surrounding the lower end portion of the pin, an annular downwardly facing shoulder at the lower end of said upper body section surrounding its recess, said lower body section having an annular upwardly opening recess in its upper end surrounding the lower end of said pin, the recesses being substantially complementary and in communicating alinement for forming an annular chamber in coaction with said pin, said lower body section having a plurality of spaced longitudinal grooves coextensive with its exterior and communicating with its recess, cutter elements having shanks complementary to and removably mounted in the grooves, arcuate heads at the inner portions of the upper ends of the shank and extending transversely thereof for engagement within the chamber when said shanks are mounted in said grooves, the heads being complementary to said chamber and coacting to circumscribe said pin, said heads and chamber being of substantially equal radial width, and upwardly facing shoulders at the upper ends of said shanks externally of said heads for engaging the downwardly facing shoulder of said upper body section, said heads having upper and lower faces adapted to engage the top and bottom walls of said chamber simultaneously with the engagement of said shoulders whereby the cutter elements are confined against axial, radial and rotational displacement.

2. A drill bit assembly as set forth in claim -1 wherein the shoulders of the upper body section and of the shanks of the cutter elements, the upper and lower faces of the heads of said cutter elements and the top and bottom walls of the chamber are flat and in .parallel relation to one another.

3. A drill bit assembly as set forth in claim 1 wherein the shoulders of the upper body section and of the shanks of the cutter elements, the upper and lower faces of the heads of said cutter elements and the top and bottom walls of the chamber are perpendicular to the longitudinal axis of the body whereby the loads imposed on said cutter elements are directed axially of said body.

4. A drill bit assembly as set forth in claim 1 wherein the height of the heads of the cutter elements is substantially equal to the combined depth of the recesses of the body sections whereby the exterior portions of said body sections substantially surround said heads.

5. A drill bit assembly as set forth in claim 1 including webs extending between the outer arcuate surfaces of the heads and the shanks of the cutter elements and having upper surfaces flush with the shoulders of said shanks for engagement by the shoulder of the upper body section to amplify the surficial contact with said shoulder,

the recess of the lower body section being enlarged complementarily to the webs for receiving the same whereby said webs coact with said shanks to prevent rotational displacement of said cutter elements.

6. A drill bit assembly as set forth in claim 1 wherein the heads upstand from the shanks of the cutter elements, the recess of the upper body section being of greater depth than the recess of the lower body section whereby the major portions of said heads are confined within said upper body section recess.

7. A drill bit assembly as set forth in claim 1 including an upwardly facing shoulder at the upper end of the lower body section in surrounding relation to its recess and flush with the shoulders of the shanks of the cutter elements for simultaneous engagement with the shou1- der of the upper body section, the upwardly facing shoulder being interrupted by the longitudinal grooves of said lower body section.

8. A drill bit assembly as set forth in claim 7 wherein the shoulders of the upper and lower body sections and of the shanks of the cutter elements, the upper and lower faces of the heads of said cutter elements and the top and bottom walls of the chamber are fiat and in parallel relation to one another.

9. A drill bit assembly as set forth in claim 7 wherein the shoulders of the upper and lower body sections and of the shanks of the cutter elements, the upper and lower faces of the heads of said cutter elements and the top and bottom walls of the chamber are perpendicular to the longitudinal axis of the body whereby the loads imposed on said cutter elements are directed axially of said body.

10. A drill bit assembly as set forth in claim 7 including webs extending between the outer arcuate surfaces of the heads and the shanks of the cutter elements and having upper surfaces flush with the shoulders of said shanks for engagement by the shoulder of the upper body section to amplify the surficial contact with said shoulder, the recess of the lower body section being enlarged complementarily to the webs for receiving the same whereby said webs coact with said shanks to prevent rotational displacement of said cutter elements.

11. A drill bit assembly as set forth in claim 7 wherein the heads upstand from the shanks of the cutter elements, the recess of the upper body section being of greater depth than the recess of the lower body section whereby the major portions of said heads are confined within said upper body section recess.

References Cited UNITED STATES PATENTS 2,498,251 2/ 1950 Creel -412 2,831,657 4/1958 Hawthorne 175-412 2,861,779 11/1958 White 175-412 2,978,049 4/ 1961 Skidmore 175-413 X CHARLES E. OCONNELL, Primary Examiner. NYLE C. BYERS, JR., Assistant Examiner. 

1. A DRILL BIT ASSEMBLY INCLUDING A BODY HAVING UPPER AND LOWER TUBULAR SECTIONS, A TUBULAR PIN UPSTANDING AXIALLY FROM THE LOWER SECTION AND SCREWTHREADED IN THE BORE OF THE UPPER SECTION FOR CONNECTING THE BODY SECTIONS TO EACH OTHER, THE LOWER END OF THE BORE OF SAID UPPER BODY SECTION BEING ENLARGED TO PROVIDE AN ANNULAR DOWNWARDLY OPENING RECESS SURROUNDING THE LOWER END PORTION OF THE PIN, ANNULAR DOWNWARDLY FACING SHOULDER AT THE LOWER END OF SAID UPPER BODY SECTION SURROUNDING ITS RECESS, SAID LOWER BODY SECTION HAVING AN ANNULAR UPWARDLY OPENING RECESS IN ITS UPPER END SURROUNDING THE LOWER END OF SAID PIN, THE RECESSES BEING SUBSTANTIALLY COMPLEMENTARY AND IN COMMUNICATING ALINEMENT FOR FORMING AN ANNULAR CHAMBER IN COACTION WITH SAID PIN, SAID LOWER BODY SECTION HAVING A PLURALITY OF SPACED LONGITUDINAL GROOVES COEXTENSIVE WITH IS EXTERIOR AND COMMUNICATING WITH ITS RECESS, CUTTER ELEMENTS HAVING SHANKS COMPLEMENTARY TO AND REMOVABLY MOUNTED IN THE GROOVES, ARCUATE HEADS AT THE INNER PORTIONS OF THE UPPER ENDS OF THE SHANK AND EXTENDING TRANSVERSELY THEREOF FOR ENGAGEMENT WITHIN THE CHAMBER WHEN SAID SHANKS ARE MOUNTED IN SAID GROOVES, THE HEADS BEING COMPLEMENTARY TO SAID CHAMBER AND COACTING TO CIRCUMSCRIBE SAID PIN, SAID HEADS AND CHAMBER BEING OF SUBSTANTIALLY EQUAL RADIAL WIDTH, AND UPWARDLY FACING SHOULDERS AT THE 